In an ink-jet recording apparatus which discharges ink from a recording head to a medium, the recording head is provided with a nozzle having a plurality of small opening portions formed therein and with a pressure chamber communicating with the nozzle.
The pressure chamber has a wall face partially formed of piezoelectric element. The piezoelectric element vibrates such that a voltage applied to the piezoelectric element can change the volume of the pressure chamber.
FIG. 5 shows a typical example of the voltage applied to the piezoelectric element.
Referring to the example, the voltage applied to the piezoelectric element is first reduced from a voltage VH at which the interior of the pressure chamber is contracted to a voltage VL at which the interior of the pressure chamber is expanded. Subsequently, the voltage VL is maintained to wait for the timing for discharging ink.
Then, the voltage applied to the piezoelectric element is increased to VH to set the interior of the pressure chamber in the contracted state. Since the interior of the pressure chamber is contracted at this point, the ink is discharged from the nozzle.
In an ink-jet recording apparatus disclosed in Patent Literature 1, a pressure chamber is first contracted to raise a central area of a meniscus of ink at a nozzle opening portion of a recording head toward a media to start the discharge of the ink. By the time when the speed of a rear end portion of the ink starting to be discharged at the nozzle opening portion reaches zero, an expansion step is performed in which the pressure chamber is expanded to pull an outer edge portion of the meniscus, the central area of which was raised at the contraction step.
According to such a method, only the drop of ink starting to be discharged is discharged.